Oscillating drive means



Oct. 24, 1967 a mwsanm OSCILLATING DRIVE MEANS 2 Sheets-Sheet 1 Filed Dec. 6, 1966 ATTORNEYS Oct. 24, 1967 -LEV 3,34%,262

' OSCILLATING DRIVE MEANS Filed Dec 6, 1966 2 Sheets-$heet 2 INVENTOR l APERToN B. HORSLEY ATTORN EYS ,only that greatly reduced amount which United States Patent 3,349,261 OSCILLATING DRIVE MEANS Caperton B. Horsley, East Walpole, Mass., assignor to Braxton Corporation, Medfield, Mass., a corporation of Massachusetts Filed Dec. 6, 1966, Ser. No. 607,113 7 Claims. (Cl. 310-36) ABSTRACT OF THE DISCLOSURE A material treating system having balanced masses elastically coupled through a torsion bar for resonant frequency oscillation in opposite phase. Electrodynamic drive means for driving the system are utilized.

This application is a continuation-impair of my copending US. application Ser. No. 400,500, filed Sept. 28, 1964 now abandoned.

This invention relates to torsionally oscillating resonant systems, and more particularly to torsionally oscillating resonant systems provided with improved means for driving the same.

By a torsionally oscillating resonant system is meant a two-mass system of the type shown and described in US. Patents Nos. 2,584,053 and 2,625,379, wherein an action mass and an equal or balancing reaction mass are coupled by a torsion bar in a spring lever system having a resonant frequency of vibration at or near which its total mass is effectively zero, and the power needed to excite or stimulate the inertia-less system is is required to work the material being treated, and to overcome losses.

Torsionally oscillating resonant systems such as here concerned have a number of uses and applications, such as for refining paper pulp, as by torsional oscillation of blades; for dispersing pigments in a liquid, as by torsional oscillation of discs; or for separating small solid particles of diiferent size ranges, as by the torsional oscillation of a system of slots or holes.

A torsionally oscillating resonant system of this invention, characterized more particularly by the invention drive means, will herein be specifically considered, by way of example, which has application to the refining of paper pulp, as a step in the manufacture of paper.

The object in refining paper pulp, such as a wood fiber and water slurry, is more generally to impart maximum strength and uniformity to the paper product, and more particularly to enhance particular properties that may be desired for particular papers. The uniformity of the ultimate product that results from the refining of the paper pulp, or the mechanical working of the fiber-water slurry, is accomplished through altering the'cellulose fibers in the respects of: deshiving, or separating the fiber bundles into individual fibers; fibrillation, or separation of some of the hair-like fibrils from the main body of the fiber, lmaking it fuzzy; and hydration, or softening and wetting the fiber, hemicellulose to the outside, thus improving its ability to bond to other fibers.

There are a variety of conventional equipments, such as Jordans, Clafiins, heaters, andthe like, which have long been employed to accomplish the refining of paper pulp. With these prior devices, however, the working or stressing of the fibers is not uniform, and accurate or close control of the fiber treatment cannot be attained.

It is also a principal objective in pulp refining to accomplish the foregoing beneficial changes in the cellulose fibers at the least possible compromise of, or with minimum reduction in, the length of the fiber and the freeness of the pulp slurry, as well as with the lowest possible and working some of its internal 3,349,261 Patented Oct. 24, 1967 cost or consumption of power. To conserve consistently the fiber length and freeness requires a pulp refining process or technique which is characterized by uniformity of fiber treatment, or which more particularly afiords control of the stress to which each fiber is subjected during the refining process. Without such control, some of the pulp may be, for example, over-refined, with the result that many of its fibers are so broken down into their constituent fibrils as to lower the pulp slurry freeness without providing a proportional increase in paper strength.

The conventional pulp refining equipments are all incapable of achieving the desired uniform close control of the treatment of the fibers, as just mentioned, due to an inherent characteristic by which these prior devices are commonly disadvantaged. Specifically, and with the Jordan, for example, the fibers are made to pass between blades or segments which are rotating with respect to each other. More particularly an elongated rotating member having longitudinal ribs or segments thereon is positioned to abut a like elongated stationary member having similar ribs or segments, and is actuated such that its segments continuously sweep or brush past the juxtapositioned segments of the stationary member. In this the rotary member segments are successively closed to and opened from contact, or substantial contact, with the stationary member segments at their narrow longitudinal edges or ends.

The refining action of the prior devices on the slurry fibers is, then, to trap or catch some of the fibers on the leading edge of the segments of the rotating member and pinch them between the edgewise abutted rotary and stationary member segments, but also to carry or flow others of the fibers, or those fibers that are carried between the rotating segments, past the stationary segments without subjecting them to any pinching action whatsoever.

It will thus be seen that the action of the prior refining apparatus on the pulp fibers is non-uniform and uncontrolled, and is characterized by a random pattern of fiber stressing ranging from the described pinching of some to the indicated bypassing of others of the fibers in the slurry.

The herein concerned fluid material treating apparatus, or torsionally oscillating resonant system, such' as incorporates an improved drive means in the invention embodiment, improves upon the described prior devices by novel provision for uniformity of fiber treatment, and

more particularly for complete and accurate control of '50 percent, in resistance to tear.

The improved pulp refining apparatus hereof, in contrast to the continuous or unidirectional prior devices, is characterized by a reciprocating or oscillating movement, and comprises generally a system by which the pulp slurry may be treated or subjected, in varying controlled 'degrees, to periodic pressure changes, or alternating acceleration, or alternating shear, or combinations thereof. These conditions are attained in a container in which the pulp slurry is passed through fiber treating means comprising one or more annular plates or discs of metal construction, and which are radially cut to present or form them as blade segments. For some applications oscillating and stationary blades are stacked in pairs, arranged with the blades coaxially mounted for continuous en- 3 gagement, or substantial engagement, at their constantly juxtaposed sides, as contrasted with the prior intermittent engagement of momentarily juxtaposed rib peripheries.

In operation the moving blade of each pair is oscillated at a very rapid rate and at an amplitude or displacement suificient to produce very large peak alternating accelerations. In one practical embodiment of the oscillating apparatus, for example, a blade of 3-0 inches diameter is oscillated at 240 cycles per second, with a total displacement of about 0.375, +0.1 875 inch, thus providing a peak acceleration of about 1080 G. With this arrangement the oscillating blades may be predeterminedly forced against the stationary blades so that the slurry fibers are subjected to the desired intensity of alternating shear forces.

It will be seen that in the alternating or oscillating action as just described, and when slurry fibers are caused to pass between a blade pair, each fiber is subjected to substantially the same treatment as every other fiber.

,Whereas, if the moving blades were rotated in one direction only, the result would be the same as with the Jordans and beaters; namely, while some groups of fibers would be pinched, other groups thereof would flow through the blades without being pinched. Further, by

varying the force with which the oscillating blades are pressed towards the stationary blades, andalso by varying the pulp consistency, almost any desired peak alternating stress of the fiber can be obtained.

At frequencies of alternation of 2-00 c.p.s. or more, and with accelerations of 1,000 G or more, the fibers in a thick slurry are effectively decoupled so that the slurry will flow through small openings, almost like a pure liquid. Specifically, at 220 c.p.s. and 1,000 G peak alternating acceleration a 3 percent consistency slurry will flow through openings two or three thousandths of an inch wide, or which are just a little larger than the diameter of the fibers themselves.

It will be appreciated that the alternation of the disc or blade masses through the indicated large displace ments requires the overcoming of correspondingly large inertias, the force needed to overcome the inertias being, in fact, more than ten times the force required to overcome the friction of the pulp slurry against the blades.

With fluid material treating or refining apparatus of the rotary oscillating type just described, a solution to the blade inertia problem is provided by the two-mass, torsionally oscillating resonant system here concerned. In such system, the blade mass is balanced by an opposite mass, i.e. the reaction mass, to which it is coupled by a torsion bar so that by twisting this bar the two masses may be coaxially oscillated in 180 phase relation. That is, in the alternation or reciprocation the masses rotate oppositely, their opposite movement of rotation proceeding until their inertia is counterbalanced by the force which such movement stores up in the torsion bar, whereupon they reverse direction. And in this opposing, reversing rotation the torsion-spring-coupled masses are reciprocated or vibrated at the resonant frequency of the systern, at which the mass of the blades becomes effectively zero, and relatively little power or energy is required to drive the system.

Torsionally oscillating resonant systems as here concerned have heretofore been operated or driven by a crankshaft connected to the reaction mass through an actuating spring arm. In such prior drive means the crankshift is driven in turn by a variable speed, wound rotor, alternating current motor, the speed of which is controlled or adjusted to set or maintain the desired amplitude of blade oscillation, by approaching or receding from the peak resonant frequency.

Such crankshaft systems are subject to serious difli- -culties, particularly in that substantial mechanical or friction losses are experienced, and in that safe opera- ,tion imposes limits on the power by which the torsionally oscillating resonant system can be operated, and there- 4 fore on the size and life-expectancy with which the system can be invested.

Electrodynamically actuated vibrators or shakers are also known, and have been employed heretofore such as for fatigue test purposes. However, these prior shakers generally produce very little power. The power capacity of the shakers is strictly limited because of the inertia of the shaker armature. The inertia of the armature will be understood to result in a force restraining the alternating movement. Thus, since with these shakers the alternating movement, and hence the velocity, is very small, an excessively high force would be required in order to produce appreciable power.

In accordance with this invention, a torsionally oscillating resonant system is provided in which is employed an electrodynamic drive, and of which drive the armature is made an integral part of the resonant system, whereby the armature inertia is reduced effectively to zero, large peak armature velocities are obtained, and large amounts of power are provided to the oscillating system with the employment of such smaller force than would be required were it not, in effect, inertia-less.

Accordingly, it is an object of this invention provide a torsionally oscillating resonant system having a drive means which is free from the strains and distorting forces associated with the prior mechanical linkage and springarm drive means.

Another object of the invention is to provide a torsionally oscillating resonant system improved by a drive means which is free from the mechanical friction losses of the prior drive mechanism.

Yet another invention object is to provide a torsionally oscillating resonant system and electrodynamic drive therefor having various applications such as to the processing of fluid materials and otherwise.

Still another invention object is to provide a torsionally oscillating resonant system with an electrodynamic actuator which, in contrast to the prior'mechanical drive, has longer life, less maintenance, lower cost and few parts, with no high-speed shafts or gears.

A further invention object is to provide a torsionally oscillating resonant system with electrodynamic drive wherein the drive armature is so incorporated in the system as to have zero effective mass, and hence to free the system from restraint of its oscillation by the inertia of the armature, whereby substantial power may be supplied to the system without excessively high currents and mignetic fields which would not only greatly increase the cost, but also greatly reduce the efficiency.

Referring now to the drawings;

FIG. 1 is a perspective view of a torsionally oscillating resonant system of and incorporating an improved drive means of this invention, and which is partially broken away to show the oscillating blades and the pulp flow paths; and

FIG. 2 is a like perspective view on a larger scale of an improved electrodynamic drive as comprised in the torsionally oscillating resonant system of FIG. 1.

In FIG. 1 a torsionally resonant system of an incorporating the improved electrodynamic drive of the invention is shown as comprising two masses, a first or blade mass 10 consisting of one or more annular, radially cut or toothed oscillating blades, and a second or reaction mass 11 consisting of one or more armature discs or spoked wheels, hereinafter to be further described. The two masses 10, 11 are coaxially joined together through a bar or tube 12, to which they may be variously attached as by rings, drums, or other conventional means, not shown. To adapt the system for oscillation of the masses 10,11 in the relation out of phase with each other, the member 12 is constructed as a spring couple -or torsion bar.

The dimensions or spring characteristics of the torsion bar 12 are chosen in relation to the masses 10, 11 such that, taking into account the additional masses and frictional effects of the pulp refining system, the oscillating system will have a natural frequency of torsional oscillation which corresponds with the desired operating frequency. The operation of the hereinafter mentioned drive means is, then, to excite the system to oscillate at the desired or predetermined operating frequency, which is one to which the resonant frequency of the system is chosen to be close.

In the resonant frequency oscillation the desired amplitude of motion may be maintained without excessive loads having to be applied to the driving means because a system of the described characteristics will then have, in effect, zero mass, with the inertial forces in balance. Again and more particularly, the inertial forces are balanced since the equal masses 10, 11 are oscillating in opposite phase, and the only power which the drive need furnish is therefore that required to compensate for damping losses inherent in the system, and to supply the power absorbed by the pulp.

For fluid-material refining, the torsionally resonant system may be enclosed in a housing 13, in which it may be located by conventional bearings, not shown, and in which may be carried also a sleeve or ring 14 to which may be fixed or clamped the fixed material treating blades, also not shown. As already explained, the fixed blades may be laterally disposed annular discs radially cut to present vertical pulp flow passages over which are centered in closely spaced, overlapping relation the radial blades of the moving discs.

The housing 13 is provided further with an inlet passage 15 communicating with an annular manifold through which the pulp chamber slurry may be introduced and flowed centrally to the treating blades 10, for passage perpendicular to said blades, and thence to a refined pulp slurry outlet 16. The slurry or slurry content rejected or not passed by the blades is overflowed to a passage 17 Without the ring 14, and lying between it and the housing 13, whereby the bypassed slurry can then pass to an overflow outlet 18, from which it may be discharged to be disposed of, or to be returned to the inlet 15, for additional passes through the apparatus. The FIG. 1 apparatus further comprises a pressure control means or link 19 connected as shown between the blades and the displacement minimum node or nodal point of the torsion bar 12, whereby upon adjustment of the link the spacing of the discs of the stationary-oscillating blade pairs, and thereby the pressure on the slurry fibers, may be controlled or pre-set as desired.

In accordance with the invention, the reaction mass 11 comprises more particularly one or more armature discs, each said disc having a series of vertical passages 20 extending therethrough, said passages 20 being spaced at equal angles around the axis of the disc, and defining therebetween radially disposed portions, or spokes, of the annular disc, or wheel. The passages are positioned relatively near the periphery of the disc and have appreciable radial extent. In the illustrated embodiment of my invention, there are around the disc some six such passages, spaced approximately 60 apart at their centers; but this number may vary somewhat, depending on the size of the disc and also the power requirements of the system. In any event, for reasons that will become apparent later, there should be an even number of such passages and their number should be such, in relation to the size of the disc, that they are spaced fairly close together.

A corresponding series of transformer cores 21 are mounted adjacent the disc around the periphery thereof by any conventional fixture means, not shown. Each transformer core has one vertical inner leg 21a which extends through one of the passages in the disc. Each transformer core 21 also has a vertical outer leg 21b which extends across the plane of the disc outwardly of the disc periphery. The relative sizes of the transformer cores 21 and their passages 20 are such that when the cores 21 are mounted properly adjacent the disc, their inner 6. legs 21a do not touch the sides of the passages. Furthermore, the passages are long enough, angularly considered, to enable the discs to swing through the required angle with the stationary transformer cores 21 merely approaching, and not also touching, first one and then the other end of their corresponding passages.

A coil of insulated Wire 22 is wound about the outer leg of each of the transformer cores 21. The wire coils 22 are adapted to their ends to be connected to a source of high frequency alternating current, and are arranged each to comprise the primary winding of the transformer. In accordance With the invention, there is utilized as the secondary of each such transformer the portion 23 of the disc 11 surrounding the inner leg 21a of the transformer core 21. As above noted, the disc portions 23 have radial spoke segments intervening the passages 20, which radial spokes will be understood to have in effect zero inertia.

Further to the invention apparatus, alternate ones of the even numbered cores 21 are differentiated in that the coils 22 around the outer legs of adjacent cores are wound in opposite directions, so that when current is supplied to the coils 22, the magnetic flux flow at any given instant is in opposite directions through said alternate or adjacent ones of the cores 21.

A series of generally U-shaped magnets 24 are mounted adjacent the disc around the circumference thereof alternately with the cores. Each magnet 24 is positioned with its two poles in vertical alignment above and below the disc, and the proportioning of the magnets relative to the disc is such that a small gap or clearance is left between each pole and the upper and lower surfaces respectively of the disc.

In the form herein shown the magnets 24 will be understood to comprise electromagnets having the usual energizing coils which are adapted to be connected to a DC. voltage supply. However, magnets of the permanent variety may also be employed, and may be preferred in some applications.

As best seen in FIG. 2, adjacent ones of the magnets 24 are oppositely polarized, so that the magnets alternately have their north poles disposed above and below the disc whereby the magnetic fields of adjacent ones of the magnets correspondingly are directed downwardly and upwardly through the disc, with this alternation of field direction proceeding all the Way around the disc through the entire series of magnets which may be six in number.

In the operation of my improved drive system, the coils 22 are connected to a common source of high frequency alternating current, which source may be, for example, an alternator supplying an output frequency of 240 cycles per second. The alternating current flowing through each coil 22 gives rise to an alternating magnetic flux in the associated core 21, and since the coils 22 on adjacent cores are oppositely wound, the magnetic fluxes which they produce in their respective cores 21 will, as earlier mentioned, flow in opposite directions, at any given instant. Specifically, the instantaneous magnetic flux flow is in one core directed upwardly, and in the adjacent core directed downwardly, through the disc 11.

These alternating fluxes flowing through the transformer cores 21 induce electric currents in those portions of the disc 11 that are in the immediate vicinity of the cores. In the illustrated embodiment these induced currents flow in circular paths about the passages 20' through the disc. During the positive half cycle of the input signal the current induced by each transformer core 21 will flow in a circular path in one direction about each core, say, the direction indicated by the solid arrows in FIG. 2. During the negative portion of the input signal, the induced currents will follow oppositely directed circular paths, indicated by the dotted arrows in FIG. 2.

It is apparent from FIG. 2 that because the transformer cores alternate in polarity, the currents which adjacent cores 21 induce in the disc portions lying between them have the same direction. For example, the left-hand pair of cores in FIG. 2 induce currents in the intervening disc portion which flow radially inwardly toward the disc center during the positive half of the input signal as indicated by the solid arrows; and during the negative half of the signal said adjacent left-hand cores will both induce a current flow radially outward toward the periphery of the disc, in said disc portion lying therebetween, and as shown by the dashed arrows.

The center pair of cores 21, on the other hand, induce currents in the portion of the disc lying between them which flow radially outward toward the rim of the disc during the positive half of the input signal, and which flow toward the center of the disc during the negative half of the signal.

Similarly directed currents are similarly induced in the disc portions between the successive pairs of transformer cores all around the disc, during the positive and negative halves of the input signal, as made clear by the solid and dashed arrows indicating current directions in said positive and negative signal halves respectively. Thus radially inwardoutward flow of the transformer induced currents in the disc regions between the cores is laterally along the disc 11 and is also directed, it will be understood, perpendicular to the magnetic fields applied from the magnets 24.

These induced currents flowing in the disc portions interleaving the poles of the magnets develop a force which is directed perpendicular to the direction of current flow and also to the direction of the applied magnetic fields in accordance with the well-known right-hand rule. Thus for the left-hand magnet of FIG. 2, during the positive half cycle of the input signal, the induced currents flowing radially inward toward the center of the disc between the upper north pole and lower south pole of the magnet, generate a force which tends to move the disc to the left, or clockwise about its axis.

At the same time, the radially outwardly directed currents flowing in the disc portion between the second and third cores (counted from left to right), when subjected to the upwardly directed applied magnetic field from the upper south pole magnet there also imparts a force to the disc tending to turn that to the left, or in a clockwise direction as indicated by the solid arrow drawn about the axis of the disc 11.

The operation is the same with respect to the remainder of the magnets disposed around the disc; in this the relationships throughout, between the direction of the currents induced in a disc portion and the direction of the magnetic field applied there, are such that the forces produced are all additive and tend to turn the discs in the same or clockwise direction, during the positive portion of the input signal. In other words, when the direction of the applied magnetic field is down, the induced currents directed radially through that field toward the center of the discs produce a force, urging the near side of the disc to the left. And where the magnet polarity is such that the direction of the field is up, the induced current flow is radially outward of the disc, so as also to produce a force driving the discs to the left (as considered from the front), or in the clockwise direction.

During the negative portion of the input signal the induced currents flow in the reverse direction, as indicated by the dashed arrows. When subjected to the same magnetic fields from the magnets, these oppositely directed currents give rise to an applied force tending to move the disc to the right or counterclockwise as indicated by the dashed arrows around the axis of the disc, FIG. 2, in accordance with the aforementioned right-hand rule.

In the operation of the invention drive means, then, the disc 11 undergoes a swing to the left, and then a swing to the right, through one full cycle of the applied signal. Successive cycles of the signal will, therefore, cause the disc to oscillate back and forth. And in this oscillation the amplitude, or displacement, of the oscillating disc increases as energy is being stored in the resonant system,

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention, which as a matter of language, might be said to fall therebetween.

I claim:

1. A torsionally oscillating resonant system for treatment of material comprising an action mass having a treating surface adapted to contact said material, a reaction mass balancing said action mass, a torsion bar elastically coupling said masses for oscillating in opposite phase, said masses and bar comprising a system having a resonant frequency of vibration at which said masses oscillate at the same frequency but in said opposite phase, and at which frequency the mass of said action and reaction masses is thereby reduced effectively to zero, and an electrodynamic drive for said system, said drive comprising an armature disc formed by said reaction mass, radial spokes formed in said armature disc, means for generating magnetic field flux across said spokes, and means for inducing alternating current flow through said spokes at said resonant frequency, whereby a torsional driving force is produced on said armature disc mass, and whereby by virtue of the effectively zero inertia of said reaction mass said system may be stimulated to generate high armature velocity, and hence high power out-put, with but low-force currents and fields applied to said radial spokes of said mass.

2. A system according to claim 1, wherein said armature disc spokes are provided in even number and wherein said alternating currents and fields are instantaneously in opposite directions through adjacent spokes, such that at any instant the driving force on said disc is in the same direction at all said spokes.

3. A torsionally oscillating resonant system for treatment of material comprising an action mass having a treating surface adapted to contact said material, a reaction mass balancing said action mass, a torsion bar elastically coupling said masses for oscillating in opposite phase, said masses and bar comprising a system having a resonant frequency of vibration at which said masses oscillate at the same frequency but in said opposite phase, and at which frequency the mass of said action and reaction masses is thereby reduced effectively to zero, and an electrodynamic drive for said system, said drive comprising an electrically conducting disc constructed and arranged as said reaction mass of said material treating system, means for inducing an alternating, radially outward and inward directed current flow in said disc, and means for producing magnetic flux vertically directed through said disc and so as to intercept said alternating radially directed current flow, whereby a rotary driving force is produced on said disc which is effective to oscillate said disc upon the inducing and alternating of said current flow at or near the resonant frequency of said system.

4. A torsionally oscillating resonant system for treatment of material comprising an action mass having a treating surface adapted to contact said material, a reaction mass balancing said action mass, a torsion bar elastically coupling said masses for oscillating in opposite phase, said masses and bar comprising a system having a resonant frequency of vibration at which said masses oscillate at the same frequency but in said opposite phase,

disc, a magnetic flux core mounted fixedly adjacent said disc, said flux core having a portion extending through said passage, said passage being sufficiently larger than said core portion to enable said disc to rotatively oscillate relative to said fixed core, means for producing an alternating magnetic flux in said core and thereby inducing an alternating current in portions of said disc around said passage, a magnet fixedly mounted in juxtaposition to said disc, and with its opposite spokes slightly spaced from the opposing faces of said disc, said magnet poles being juxtaposed also to the portions of said disc adjacent said passage wherein said current flows in substantially radial directions, whereby upon the inducing and alternating of said current flow at or near the resonant frequency of said system a rotary driving force is produced on and which is effective to oscillate said disc mass.

5. A torsionally oscillating resonant system for treatment of material comprising an action mass having a treating surface adapted to contact said material, a reaction mass balancing said action mass, a torsion bar elastically coupling said masses for oscillating in opposite phase, said masses and bar comprising a system having a resonant frequency of vibration at which said masses oscillate at the same frequency but in said opposite phase, and at which frequency the mass of said action and reaction rnasses is thereby reduced effectively to zero, and an electrodynamic drive for said system, said drive comprising an electrically conductive plate arranged as the reaction mass of and for oscillation in said system, means defining a passage extending through said plate, a magnetic flux core fixedly mounted adjacent said plate and having a portion extending through said passage, said core portion and said passage being relatively dimensioned for some freedom of oscillating movement of said plate relative to said core portion, means for producing an alternating magnetic flux in said core and so as to induce in said disc an alternating current traveling in opposite directions in disc portions around said passage, and magnet means fixedly mounted in juxtaposition to said disc and having opposite poles slightly spaced from the opposing faces of said disc, said magnet poles being juxtaposed to those of said disc portions around said passage wherein the opposite traveling of said current is in directions substantially perpendicular to said one and the reverse direction of oscillation, whereby, upon the inducing and alternating of said current, a force is produced at right angles to said perpendicular current flow and said flux and which is effective to drive said plate in said one and the reverse oscillating direction.

6. A torsionally oscillating resonant system for treatment of material comprising an action mass having a treating surface adapted to contact said material, a reaction mass balancing said action mass, a torsion bar elastically coupling said masses for oscillating in opposite phase, said masses and bar comprising a system having a resonant frequency of vibration at which said masses oscillate at the same frequency but in said opposite phase, and at which frequency the mass of said action and reaction masses is thereby reduced effectively to zero, and an electrodynamic drive for said system, said drive comprising an electrically conducting disc constructed and arranged as said reaction mass of said material treating system, a magnetic flux core fixedly mounted adjacent said disc and so as to allow a desired degree of oscillation of said disc relative to said fixed core, means for producing an alternating magnetic flux in said core and so as to induce in said disc an alternating current flowing radially outwardly and inward in disc portions to either side of said core, at least one pair of magnets fixedly mounted in juxtaposition to said disc portions, and said magnets arranged to have opposite polarity, whereby to produce a force acting in the same direction at right angles to said current flow and said magnetic flux and effective to drive said disc mass in one and the opposite direction upon the inducing and alternating of said current flow.

7. A torsionally oscillating resonant system for treatment of material comprising an action mass having a treating surface adapted to contact said material, a reaction mass balancing said action mass, a torsion bar elastically coupling said masses for oscillating in opposite phase, said masses and bar comprising a system having a resonant frequency of vibration at which said masses oscillate at the same frequency but in said opposite phase, and at which frequency the mass of said action and reaction masses is thereby reduced effectively to zero, and an electrodynamic drive for said system, said drive comprising an electrically conducting disc comprises in the reaction mass of said material treating system, an even plurality of passages through said disc, an even plurality of magnetic flux cores fixedly mounted adjacent said disc and each having portions extending through a respective passage, said passages and core portions being relatively proportioned for some freedom of oscillating movement of said disc relative to said core portions, means for producing an alternating magnetic flux in said core portions and so as to induce in said disc alternating current flowing radially inward and outward in disc portions intermediate the portions occupied by said passages and core portions, an even plurality of magnets fixedly mounted in juxtaposition to said intermediate disc portions, said magnets alternately of opposite polarity whereby to produce a force acting in a direction at right angles to said current flow and said magnetic flux and effective to drive said disc mass in one and the opposite direction upon the inducing and alternating of said current flow at or near the resonant frequency of said system.

References Cited UNITED STATES PATENTS 2,584,053 1/1952 Seavey et al. 259-4 2,774,016 12/1956 Matthews et al 310-38 X 3,159,760 12/1964 Olofsson 310-166 MILTON O. HIRSHFIELD, Primary Examiner. D. F. DUGGAN, Assistant Examiner. 

7. A TORSIONALLY OSCILLATING RESONANT SYSTEM FOR TREATMENT OF MATERIAL COMPRISING AN ACTION MASS HAVING A TREATING SURFACE ADAPTED TO CONTACT SAID MATERIAL, A REACTION MASS BALANCING SAID ACTION MASS, A TORSION BAR ELASTICALLY COUPLING SAID MASSES FOR OSCILLATING IN OPPOSITE PHASE, SAID MASSES AND BAR COMPRISING A SYSTEM HAVING A RESONANT FREQUENCY OF VIBRATION AT WHICH SAID MASSES OSCILLATE AT THE SAME FREQUENCY BUT IN SAID OPPOSITE PHASE, AND AT WHICH FREQUENCY THE MASS OF SAID ACTION AND REACTION MASSES IS THEREBY REDUCED EFFECTIVELY TO ZERO, AND AN ELECTRODYNAMIC DRIVE FOR SAID SYSTEM, SAID DRIVE COMPRISING AN ELECTRICALLY CONDUCTING DISC COMPRISES IN THE REACTION MASS OF SAID MATERIAL TREATING SYSTEM, AN EVEN PLURALITY OF PASSAGES THROUGH SAID DISC, AND EVEN PLURALITY OF MAGNETIC FLUX CORES FIXEDLY MOUNTED ADJACENT SAID DISC AND EACH HAVING PORTIONS EXTENDING THROUGH A RESPECTIVE PASSAGE, SAID PASSAGES AND CORE PORTIONS BEING RELATIVELY PORPORTIONED FOR SOME FREEDOM OF OSCILLATING MOVEMENT OF SAID DISC RELATIVE TO SAID CORE PORTIONS, MEANS FOR PRODUCING AN ALTERNATING MAGNETIC FLUX IN SAID CORE PORTIONS AND SO AS TO INDUCE IN SAID DISC ALTERNATING CURRENT FLOWING RADIALLY INWARD AND OURWARD IN DISC PORTIONS INTERMEDIATE THE PORTIONS OCCUPIED BY SAID PASSAGES AND CORE PORTIONS, AN EVEN PLURALITY OF MAGNETS FIXEDLY MOUNTED IN JUXTAPOSITION TO SAID INTERMEDIATE DISC PORTIONS, SAID MAGNETS ALTERNATELY OF OPPOSITE POLARITY WHEREBY TO PRODUCE A FORCE ACTING IN A DIRECTION AT RIGHT ANGLES TO SAID CURRENT FLOW AND SAID MAGNETIC FLUX AND EFFECTIVE TO DRIVE SAID DISC MASS IN ONE AND THE OPPOSITE DIRECTION UPON THE INDUCING AND ALTERNATING OF SAID CURRENT FLOW AT OR NEAR THE RESONANT FREQUENCY OF SAID SYSTEM. 